The invention relates to a drive for rotary anodes of X-ray tubes according to the preamble of patent claim 1.
Rotary anodes are, as is known, driven with a constant angular velocity (rotational frequency) of the anode. In the case of presently conventional installations, these rotational rates correspond to frequencies of 50 Hz, 150 Hz or 300 Hz, respectively. In the case of conventional radiographs, this is a good idea because the exposure times are short here and one wishes to utilize the full tube power. After a complete radiograph the anode is again braked in order to keep the running times as short as possible and thus to preserve the ball bearings.
In a further development of the objective of preserving the ball bearings of rotary anode X-ray tubes, one could proceed from applying rotational speeds which are as low as possible. However, this would effect a reduction in the loading capacity because, as is known, the latter increases with increased rotational frequency. Therefore, it is not possible, in particular, in the case of the radiographic methods conventional today, which demand high power, to reduce the rotational speeds.